Here are some keywords to describe the lectures. You can use them for revision or to catch up on classes you missed. As always, there will be nothing here that you could not find out in class.

Jan 4. Class 1

Principles of neural coding 1

• Electrode, Microelectrode, Micron (1/1000th mm)
• membrane, nucleus, cytoplasm, Neuron, axon, dendrite, Schwann cell/glial cell, myelin sheath, node of Ranvier, Synapse, synaptic cleft, vesicle, neurotransmitter
• receptors, ions, permeability, ion channels, voltage-dependent sodium channels, neural threshold, positive feedback, sodium (Na+), potassium (K+), sodium-potassium pump, electrochemical equilibrium potentials, sodium (Na+)   +55mv, potassium (K+) -75mv, resting potential -70mv, polarization/depolarization/hyperpolarization, inhibitory post-synaptic potential (IPSP), Excitatory post-synaptic potential (EPSP)
• integration, axon hillock, action potential (AP), all-or-none, neuron threshold -55mv, saltatory propagation, AP propagation, refractory period, spontaneous firing rate

Principles of neural coding 2

• electrical stimulation (artificial depolarization of a neurone)
• spatial and temporal integration of EPSPs and IPSPs across the neurone's membrane resulting in the neuronal threshold being reached, generator potential
• sensory stimulation (transduction);  mechanical (deformation of cytoskeleton);  chemical (receptors, second messengers);  light (hyperpolarization)

• modality (Müller's doctrine of specific nerve energies 1826; labelled line)
• intensity (APs/sec; frequency coding; population coding; thresholds)
• duration (rapidly and slowly adapting neurones)
• location (absolute, two-point discrimination, topographical coding)

• across-fibre pattern coding
• population coding
• speficity coding
• channel coding

Psychophysics

Fechner, Weber, Threshold, Method of limits, staircase,  Method of constant stimuli, method of adjustment, Signal detection theory,
sensitivity versus response bias, criterion, outcome matrix, hit/miss/false alarm/false positives/correct rejection, receiver operating
characteristic curves (ROC curves), sensitivity, d-prime (d')

just noticeable difference, Weber fraction/law/constant, Fechner's law, Stevens' power law, magnitude estimation,

two alternative forced choice, standard stimulus, response compression, response expansion

Somatosensory I

1 detection
2 identify (modality)
3 identify (properties, spatial form)
4 magnitude
5 location
6 movement
 

•      which fibre?, mapping of location, identifying modality/ sub-modality
•      what pattern? frequency coding of magnitude

Somatosensory II

PART II
Revision of everything so far. Description of exam. Questions and answers session.

REVISION

Neural -- pages 3-42

REMEMBER
The exam is entirely on material taught in the class. The course kit is, on occassion, too detailed. When information is MISSING from the course kit, I have added notes under definitions (links in the keywords above).

PART II

no class

Feb 8 Class 6

somatosensory  III

•      temperature, free nerve endings, paradoxical cold
•     stereognosis,
•     temperature detection, pain, anterolateral tract (pain and temperature route), nociception, noxious stimuli, superior colliculus
•     Active touch (cookie cutters), stereognosis, Aristotle's illusion

•      Pain (perception), anterolateral tract, crossed at level of spinal cord, nociception (information), nociceptors, free nerve endings
•      referred pain, gate theory, transmission cell, inhibitory interneurones, endorphins, natural opiates, naloxone (antagonist), acupuncture

     rotation:
          semicircular canals, cupula, hair cells, angular acceleration,
          firing in nerve proportional to velocity (temporal code) and also depends on orientation of canal, need to
          compare 3 canals to decide on what the axis of rotation is (channel code)
     translation:
          otoliths (ear stones), mucus, hair cells, linear acceleration, gravity, hair cells arranged with their preferred
          directions to cover all possibilities within the plane of that otolith, utricle (horizontal plane), saccule  (vertical
          plane), despite careful arrangement of otolith hair cells most movement activates many cells (because of each one
          responding to such a broad range), most active cell found by comparing cell activity, population code
     hair cells:
          kinocilium, stereocilia, depolarization, broadly tuned to direction (+/- 90 degs), preferred direction

•      systems transduce force (mass x acceleration), angular (semicircular canals) or linear (otoliths) acceleration
•      three outputs: perception, eye movements (vestibulo-ocular reflex: VOR), postural reflexes (vestibulo-spinal reflexes),  perception, subtle sense, easily confused (because of responding to acceleration), need to construct overall movement from its parts,

•      eye movements (rotation), equal and opposite to head movement, three pairs of eye muscles whose direction of pull roughly corresponding to planes of the  canals, process required to change acceleration signal into a position signal (must be done by the brain)
•      eye movements (translation), depend on (i) head movement (ii) direction of target (eg. left or right) and (iii) distance of  target, geometry shown to be taken into account by system
•      eye movements (neural pathway), hair cells > afferent nerve (VIII) > vestibular nucleus > oculomotor nuclei > oculomotor nerves (III, IV and VI) > eye muscles
•      vestibulo-spinal reflexes, primitive (evolutionarily), but capable of remarkable complexity (organized response with many muscles)
•      multi-modal cues to self motion: vision and vestibular normally active together, vestibular nucleus responds to vision OR vestibular (or both), if visual motion provided without actual motion (eg. in a lab by moving an artificial room or in a car when the one next to you moves) it produces a convincing sensation of motion called vection (linear or circular depending on the type of motion), this is because the vestibular nucleus (and therefore the rest of the brain from there on up) cannot tell the difference between activity arising from vision or from vestibular stimulation.

•      alcohol creates illusions of self motion because of

• alcohol passes into the canals and cause fluid motion within fluid up
• so head feels moving down (pitch nose down)
• creates upward VOR
• eyes moving up in front of stationary visual world
• retinal motion down
• sensation of head moving up
• incompatible with original sensation
• inter-sensory conflict
• interpretted as poison
• vomit out poison

•      other examples of motion sickness due to sensory conflict: reading in vehicle, head movements in space, being below deck in a ship

•           Taste Primaries:  sweet, sour, salty, bitter,
•           papilla (nipple) types:  fungiform (fungus-like),  foliate (leaf-like), circumvallate (around the ramparts), filiform (no taste buds)
•           Taste buds (found on papilla except filiform),  respond to more than one ‘primary'
•           taste cells (found within taste buds), no axons, connect/synapse with afferent fibres
•           coding of quality, activity across a population,  pattern of firing of nerves related to perceptual abilities in rats (responses to different salts, ammonium, potassium and sodium chloride),  most fibres respond to more than one primary
•           taste thresholds depend on: temperature (different primaries alter differently), tongue region,  genetics (phenylthiocarbamide: to 2/3rds of white western folk tastes bitter; 1/3rd no taste),  concentration (eg. saccharin low      sweet; high bitter), age adaptation,  raising of threshold (after exposure)
•           taste preferences,  Humans: sweet (+); bitter (-),  mostly in place at birth; Cats and chickens: indifferent to sweet;rat/cat/rabbit/sheep: salt (+);  hamster: salt (-)
•           taste cravings, salt, calcium, potassium, etc.. specific changes in threshold when deprived (eg. for salt)
•           cultural influences, conditioned taste aversion
  •           neural pathway (uncrossed)
  •           taste cells,
  •           VII cranial nerves (corda tympani division of facial nerve), IX cranial nerve (glossopharyngeal),
  •           solitary nucleus,
  •           ventral posterior medial nucleus of thalamus,
  •           taste cortex (near mouth representation of somatosensory cortex),
  •           also brain stem vomit centres

MIDTERM TEST 2  (1.5 Hours): 30 multiple choice questions (75%) and 4 short
     answers (out of 6) (25%) 

   exam counts for 30% of your mark (40% if it is your best one)

     Multiple choice:    Nervous system:2
                          Psychophysics:2
                          Somatosensory system:14
                          Vestibular: 4
                          Taste: 8

     Short answers:    Nervous system: 1
                          Psychophysics:0
                          Somatosensory system:3
                          Vestibular:1
                          Taste:1

REVISION

Neural -- pages 3-42

Olfaction will not be tested on this MIDTERM

REMEMBER
The exam is entirely on material taught in the class. The course kit is, on occassion, too detailed. When information is MISSING from the course kit, I have added notes under definitions (links in the keywords above).

March 8. Class 10

olfactory binding protein, olfactory receptors cells continuously regenerate (about every 60 days),  cilia (on olfactory  receptor cells), glomerulus (contact zones between receptor cells and mitral cells: plural glomeruli), convergence (1,000:1),  mitral cell,  olfactory tubercle of entorhinal cortex (part of paleocortex),  medial dorsal nucleus of thalamus , olfactory neocortex  (orbitofrontal cortex), paleocortex associated with limbic system,  limbic system associated with emotions (electrical stimulation causes sham rage), limbic system associated with memories (lesions here cause loss in  ability to memorize things), no topographic mapping in olfactory cortex (unusual), although some hot spots in olfactory tubercle and on olfactory mucosa

odour quality,  no primaries identified in olfactory system,  poor tuning of receptors (to chemicals or chemical types) (sharpened by lateral inhibition, inhibitory interneurones, granule cells), Henning smell prism (doesn't work!), similar shaped molecules can be associated with different smell perceptions,  cells broadly tuned (responding to many different chemicals associated with many different smells) coding,  intensity= firing rate/recruitment, quality = distributed pattern code, problems in identifying many smells at once, binding problem,

odour thresholds,  olfactorium; unique technical problems!, humans very sensitive (eg. mercaton can be detected at 1 part  per 50,000,000,000),  affected by gender; can be affected by menstrual cycle,  affected by age adaptation,  thresholds raised (by exposure),  masking (by other chemicals),

identification,  can identify gender from shirt, prefer own odours, odour memories long lasting; associated with emotions (via limbic system) "designed not to forget"

pheromones,  releasers (immediate effect),  eg. bitch on heat,  territorial markers,   humans?,  McClintock effect (synchronized menstrual cycles),  primers (longer term) eg. mice need males around for proper oestrus cycles

PATHWAYS

OLFACTORY SYSTEM
     olfactory receptor cells to mitral cells in olfactory bulb to olfactory tubercle in paleocortex THEN
          1 to medial dorsal thalamus to olfactory cortex (ORBITOFRONTAL CORTEX)
          2 to limbic system

ALSO
inhibitory pathway (via inhibitory interneurone: granule cells) from one olfactory bulb to the other  to do with detecting the DIRECTION from which a smell originates
 

VOMERONASAL SYSTEM
    vomeronasal organ to accessory olfactory bulb (not in humans) to regions of the brain involved in the control of sexual behaviour.

SOMATOSENSORY SYSTEM
Free nerve endings in nose to trigeminal nerve to trigeminal nucleus to thalamus to
  1    somatosensory cortex
  2    orbitofrontal cortex (multi-modal convergence)

March 15. Class 11

1) Phonemes:

      "sounds that create meaning" 48 in English; different in different languages

2) Phonetic features:
     Voicing (2):
          voiced/unvoiced
     Place of articulation (7):
          alveolar ridge
           labiodental
           etc....
      Manner of articulation: (6)
          stop
          fricative
          nasal
          etc...

3) Acoustic signal:
      Sound spectrogram
      Formants (characteristic of vowel sounds)

4) Variability problem
      context creates variable acoustic cues eg. formant transitions because of coarticulation; its solution is an example of  perceptual constancy

5) Segmentation problem
 

Is speech special or just performed by a general auditory analysis method?

Motor theory of speech perception (yes, it is special)

      sound  > brain >  phonetic analysis >  recreate activity in vocal tracts >  phoneme identification

1) Categorical Perception
       voice onset time (VOT)
       phonetic boundary
       BUT also for non-speech sounds
        also for other species eg. monkeys, chinchillas, quail

2) McGurk Effect
       vision affects hearing
       /ga/ (lips) + /ba/ (sound) = /da/ (perception)
       links production to hearing
       BUT works with plucked/bowed cello note too

3) Are there INVARIANTS for phonemes? Something that stays the same despite different contexts, different coarticulations etc... Some hints...

TOP DOWN influences

1) Segmentation
      influenced by meaning
      "Anna Mary Candy lights since imp pulp lay things"
      "I scream, you scream, we all scream for ice cream"

 2) Semantics (meaning) and syntax (grammatical word order) both contribute to your ability to shadow (repeat what you have heard) a text

3) Phonemic restoration
      "...time to meet with their respective legi latures...."
       = cough and is moved to end of word
      "... time to  ave..." which phoneme slotted in depends on FOLLOWING words.

PHYSIOLOGY of speech perception

1) Selective adaptation
     after adapting to /ba/ a voiced syllable, phonetic boundary shifts (towards the voiced side of a boundary), suggesting a "voiced" phonetic detector
     how does /be/(sound)  + /ge/(lips) = /de/ (perception) (McGurk) affect the phonetic boundary between /de/ and /be/? Does it move towards /be/ or /de/? In other words does the perception or the acoustic cue do the adapting? ans: towards /be/, it is the acoustic cue.

2) Neural responses
      nerve show phoneme information carried in a population of fibres
      cortex cells with special requirements eg. frequency sweeps compatible with the idea of phoneme cells...

3) Lateralization of cortical function
      auditory pathways crossed
      for most people there is a right ear advantage for speech
      Broca's area underlies TALKING
      Wernicke's area underlies UNDERSTANDING

March 22. Class 12

Functions of time perception

• telling you duration
• processes that need time
  •  mathematical integration (m/s/s -> m/s)
  •  motion (m/s)
  •  use of motion (time to contact)
• telling you when to go to bed
• synchronizing mating (to annual cycle)

•  light
•  suprachiasmatic nucleus
  • lesions abolish free-running rythms
  • activity related to circadian rythms
  • isolated suprachiasmatic nucleus still cycles
•  pineal
•  melatonin

•  temperature (hot makes it faster)
•  drugs amphetamine --> slower
•  pentobarbitol --> faster

• more information takes longer
• more elements -- seems longer
• complexity -- seems longer
• ambiguous -- longer than disambiguated
• uncompleted more "memorable" and longer

• more attention is demanding and takes away from noticing how long things take
• concentrating -- faster than not concentrating
• "the watched pot never boils"

• time goes faster as you get older
• perceived time/lifespan as a constant (Weber's law)
• clock slowing down?
• dopamine depletion?

• smaller space  --> seems longer (compression of space goes along with compression of time)
• TAU  time affects distance
• KAPPA distance affects time 

March 29. Class 13

Revision

Tuesday April 26. Final exam. Steadman Lecture Theatre F at 9am.

 (2 Hours): 50 multiple choice questions (50%), 5 short
     answers (out of 10) (25%), 25 fill-in-the-blanks

   exam counts for 30% of your mark (40% if it is your best one)

     Multiple choice:    

• Nervous system:4
• Psychophysics:4
• Somatosensory system:5
• Vestibular: 6
• Taste: 3
• Smell: 8
• Speech: 14
• Time: 6

     Short answers:    

• Nervous system:2
• Psychophysics:1
• Somatosensory system:1
• Vestibular: 1
• Taste: 1
• Smell: 1
• Speech: 2
• Time: 1

    Fill in blanks

• Nervous system:3
• Psychophysics:3
• Somatosensory system:2
• Vestibular: 3
• Taste: 2
• Smell: 3
• Speech: 4
• Time: 2

REVISION
        Neural -- pages 3-42

        Speech (whole of chapter on web) pages page 172-

• each of the following sections has far too much detail, just extract the basics (at the level used in class)

• 'classification of speech sounds' (pg 179)
• 'the spectrogram' (pg 182)
• 'physical characteristics of speech sounds' (pg 186)
• 'consonants' (pg 189)
• 'motor theory of speech perception' (pg 199)

• ignore the units of speech (pg 194)

        Time pages (whole of chapter on web) pages 153-171